In APEX.oracle.com when I create a web service reference that calls the endpoint URL on an Oracle demo services environment (GSE) I get the following error:
ORA-06512: at "SYS.UTL_HTTP", line 1130 ORA-12535: TNS:operation timed out
Using a proxy didnt help, and it seems that I cant be the first person to try this. It's for an OpenWorld demo, but probably others would appreciate knowing any connectivity rules.
The exact same works fine using the Oracle Database Cloud (apex) envs.
I assume firewall is not open between systems.